Neuroimaging (part 3)

Neuroimaging (part 3)

1. EEG

   • Electroencephalography (EEG)
   • Records electrical signals generated by the brain in postsynaptic dendrite currents
   • Electrodes placed on different point of the scalps
   • Advantages
     • Good temporal resolution , when
     • Non invasive
     • Not as expensive fMRI & PET
   • Disadvantages
     • Poor spatial resolution, where

2. TMS

   • Transcranial Magnetic Stimulation
     • Allows simulated brain lesions in controls without surgery
     • Electromagnetic induction (Faraday)
     • Changes in electric current in coil generates magnetic field & induce secondary current in neurons of the site make them fire
   • Brief magnetic pulses given to a small region of cortex by a coil close to the head
     • Example : hand area in right motor cortex stimulated , P's hand will involuntary move left hand
   • Advantages
     • Can infer causality , better than fMRI studies
       • Flexible as control brain areas affected and make more comparisons
     • Good temporal resolution
     • Fairly accurate localisation (spatial resolution)
       • Kovisto , 2011
         • disrupt recurrent processing , impaired conscious visual perception
     • Environment is quiet except for loud clicks
   • Disadvantages
     • No structural info
     • P's don't like it
     • Difficult to stimulate deeper brian regions
     • P'S screened for pacemakers or epilepsy

3. NIRS

   • Near infrared spectrosopy
     • Measured through hemodynamic responses (amount of oxygenated blood) also uses BOLD response
       • Associated with neuronal behaviour
     • Uses light absorption
       • Skine , bone & tissue transparent
       • Haemoglobin is strong absorber of light
   • Advantages
     • Portable more than fMRI
   • Disadvantages
     • Poorer spatial resolution
     • Only goes 4mm deep